Finding the Fourth Proportional to 7,164.78, 9,887.70 and 3,978.08

Step by Step Solution

1. Step 1: Write the proportion equation
   7,164.78 : 9,887.70 = 3,978.08 : x
2. Step 2: Convert to fraction form
   7,164.78/9,887.70 = 3,978.08/x
3. Step 3: Cross multiply
   7,164.78x = 9,887.70 × 3,978.08
4. Step 4: Simplify right side
   7,164.78x = 39,334,032.89
5. Step 5: Solve for x
   x = 39,334,032.89/7,164.78
6. Step 6: Final answer
   x = 5,489.92